The cooling system tells you it has a problem one of two ways: you find a leak on your driveway, or the engine starts overheating. The cooling system is not maintenance-free and requires regular checks to stay in good condition.
There are a lot of flexible connections in the cooling system and this is where leaks most commonly start. The rubber hoses will begin to wear out and the joints will loosen from movement. A leak can happen anywhere in the system: the water pump can leak, the radiator can rust through, or the cylinder block can lose a gasket.
Leaks in hoses can usually be repaired easily, but leaks in big components like radiators and water pumps generally require the attention of a professional.
Leaks that aren’t addressed can lead to overheating, which leads to engine failure. Get a leak repaired right away.
The coolant in the radiator is mixed with water, and the water can bring with it minerals and deposits that will clog and corrode your radiator. When this happens, the coolant can’t pass through the tubes of the radiator and the engine overheats. If it rusts out, it will eventually drain down and cause overheating.
A mildly corroded radiator can be flushed with commercially available products, or some pros offer a power flush that really gets the radiator clean. You can flush your own radiator, but a severely corroded radiator should be replaced.
WATER PUMP FAILURE
The water pump is subject to failure in several ways.
A mechanical pump that is mounted to the engine may fail at the gasket points where it connects to the engine, or it may stop working if the engine belt driving it slips or breaks. An electric pump may fail if its internal motor dies. The bearing in the water pump can also give out. A whining sound may indicate that a water pump is about to fail.
The thermostat is responsible for regulating the flow of coolant by measuring the engine temperature and opening if the engine needs to be cooled down.
If the thermostat fails while closed or partially closed, the car will overheat because the coolant can’t flow. If the thermostat fails while open, it will take the engine a much longer time to come up to temperature, which can be hard on the oiling system and cause oil crystallization on the engine components. Don’t run your car without a properly functioning thermostat.
Coolant needs to be topped off or replaced periodically. You can check the level and condition of the coolant in the overflow tank. If the level is low, it can be “topped off” with distilled water. If it’s getting brown with contaminants or rust, it’s time to change the coolant.
HOSE CLAMP FAILURE
Hose clamps usually don’t fail unless they have been removed and reinstalled. Be careful when reinstalling hose clamps that have been stretched— they can fail on reinstallation.